The Experts below are selected from a list of 243231 Experts worldwide ranked by ideXlab platform

Catherine Orrell - One of the best experts on this subject based on the ideXlab platform.

  • treatment interruption and variation in tablet taking Behaviour Result in viral failure a case control study from cape town south africa
    PLOS ONE, 2011
    Co-Authors: Lisanoelle Ncaca, Katharina Kranzer, Catherine Orrell
    Abstract:

    Background: Understanding of the impact of non-structured treatment interruption (TI) and variation in tablet-taking on failure of first-line antiretroviral therapy (ART) is limited in a resource-poor setting. Methods: A retrospective matched case-control analysis. Individuals failing ART were matched by time on ART with 4 controls. Viral load (VL) and CD4 count were completed 4-monthly. Adherence percentages, from tablet returns, were calculated 4-monthly (interval) and from ART start (cumulative). Variation between intervals and TI (>27 days off ART) were recorded. Conditional multivariate logistic regression analysis was performed to estimate the effect of cumulative adherence 10% and TI on virological failure. Age, gender, baseline log VL and CD4 were included as possible confounders in the multivariate model. Results: 244 patients (44 cases, 200 controls) were included. Median age was 32 years (IQR28-37), baseline CD4 108 cells/mm3 (IQR56-151), VL 4.82 log (IQR4.48-5.23). 94% (96% controls, 86% failures) had cumulative adherence >90%. The odds of failure increased 3 times (aOR 3.01, 95% CI 0.81-11.21) in individuals with cumulative adherence 10% and 4.01 times (aOR 4.01, 95% CI 1.45-11.10) in individuals with TIs. For individuals with TI and cumulative adherence >95%, the odds of failing were 5.65 (CI 1.40-22.85). Conclusion: It is well known that poor cumulative adherence increases risk of virological failure, but less well understood that TI and variations in tablet-taking also play a key role, despite otherwise excellent adherence.

Katharina Kranzer - One of the best experts on this subject based on the ideXlab platform.

  • treatment interruption and variation in tablet taking Behaviour Result in viral failure a case control study from cape town south africa
    PLOS ONE, 2011
    Co-Authors: Lisanoelle Ncaca, Katharina Kranzer, Catherine Orrell
    Abstract:

    Background: Understanding of the impact of non-structured treatment interruption (TI) and variation in tablet-taking on failure of first-line antiretroviral therapy (ART) is limited in a resource-poor setting. Methods: A retrospective matched case-control analysis. Individuals failing ART were matched by time on ART with 4 controls. Viral load (VL) and CD4 count were completed 4-monthly. Adherence percentages, from tablet returns, were calculated 4-monthly (interval) and from ART start (cumulative). Variation between intervals and TI (>27 days off ART) were recorded. Conditional multivariate logistic regression analysis was performed to estimate the effect of cumulative adherence 10% and TI on virological failure. Age, gender, baseline log VL and CD4 were included as possible confounders in the multivariate model. Results: 244 patients (44 cases, 200 controls) were included. Median age was 32 years (IQR28-37), baseline CD4 108 cells/mm3 (IQR56-151), VL 4.82 log (IQR4.48-5.23). 94% (96% controls, 86% failures) had cumulative adherence >90%. The odds of failure increased 3 times (aOR 3.01, 95% CI 0.81-11.21) in individuals with cumulative adherence 10% and 4.01 times (aOR 4.01, 95% CI 1.45-11.10) in individuals with TIs. For individuals with TI and cumulative adherence >95%, the odds of failing were 5.65 (CI 1.40-22.85). Conclusion: It is well known that poor cumulative adherence increases risk of virological failure, but less well understood that TI and variations in tablet-taking also play a key role, despite otherwise excellent adherence.

Lisanoelle Ncaca - One of the best experts on this subject based on the ideXlab platform.

  • treatment interruption and variation in tablet taking Behaviour Result in viral failure a case control study from cape town south africa
    PLOS ONE, 2011
    Co-Authors: Lisanoelle Ncaca, Katharina Kranzer, Catherine Orrell
    Abstract:

    Background: Understanding of the impact of non-structured treatment interruption (TI) and variation in tablet-taking on failure of first-line antiretroviral therapy (ART) is limited in a resource-poor setting. Methods: A retrospective matched case-control analysis. Individuals failing ART were matched by time on ART with 4 controls. Viral load (VL) and CD4 count were completed 4-monthly. Adherence percentages, from tablet returns, were calculated 4-monthly (interval) and from ART start (cumulative). Variation between intervals and TI (>27 days off ART) were recorded. Conditional multivariate logistic regression analysis was performed to estimate the effect of cumulative adherence 10% and TI on virological failure. Age, gender, baseline log VL and CD4 were included as possible confounders in the multivariate model. Results: 244 patients (44 cases, 200 controls) were included. Median age was 32 years (IQR28-37), baseline CD4 108 cells/mm3 (IQR56-151), VL 4.82 log (IQR4.48-5.23). 94% (96% controls, 86% failures) had cumulative adherence >90%. The odds of failure increased 3 times (aOR 3.01, 95% CI 0.81-11.21) in individuals with cumulative adherence 10% and 4.01 times (aOR 4.01, 95% CI 1.45-11.10) in individuals with TIs. For individuals with TI and cumulative adherence >95%, the odds of failing were 5.65 (CI 1.40-22.85). Conclusion: It is well known that poor cumulative adherence increases risk of virological failure, but less well understood that TI and variations in tablet-taking also play a key role, despite otherwise excellent adherence.

Steffen Hahn - One of the best experts on this subject based on the ideXlab platform.

  • geolocation by light accuracy and precision affected by environmental factors
    Methods in Ecology and Evolution, 2012
    Co-Authors: Simeon Lisovski, Chris M Hewson, Raymond H G Klaassen, Fraenzi Kornernievergelt, Mikkel Willemoes Kristensen, Steffen Hahn
    Abstract:

    Summary 1. Geolocation by light allows for tracking animal movements, based on measurements of light intensity over time by a data-logging device (‘geolocator’). Recent developments of ultra-light devices (<2 g) broadened the range of target species and boosted the number of studies using geolocators. However, an inherent problem of geolocators is that any factor or process that changes the natural light intensity pattern also affects the positions calculated from these light patterns. Although the most important factors have been identified, estimation of their effect on the accuracy and precision of positions estimated has been lacking but is very important for the analyses and interpretation of geolocator data. 2. The ‘threshold method’ is mainly used to derive positions by defining sunrise and sunset times from the light intensity pattern for each recorded day. This method requires calibration: a predefined sun elevation angle for estimating latitude by fitting the recorded day ⁄ night lengths to theoretical values across latitudes. Therewith, almost constant shading can be corrected for by finding the appropriate sun elevation angle. 3. Weather, topography and vegetation are the most important factors that influence light intensities. We demonstrated their effect on the measurement of day ⁄ night length, time of solar midnight ⁄ noon and the Resulting position estimates using light measurements from stationary geolocators at known places and from geolocators mounted on birds. Furthermore, we investigated the influence of different calibration methods on the accuracy of the latitudinal positions. 4. All three environmental factors can influence the light intensity pattern significantly. Weather and an animal’s Behaviour Result in increased noise in positioning, whereas topography and vegetation Result in systematic shading and biased positions. Calibration can significantly shift the estimated latitudes and potentially increase the accuracy, but detailed knowledge about the particular confounding factors and the Behaviour of the studied animal is crucial for the choice of the most appropriate calibration method.

Philippe Lavoie - One of the best experts on this subject based on the ideXlab platform.

  • spatiotemporal analysis of fluctuating base pressure and velocity in a blunt trailing edge wake
    54th AIAA Aerospace Sciences Meeting, 2016
    Co-Authors: Heather A. Clark, Philippe Lavoie
    Abstract:

    Three-dimensional instabilities in the wake of a blunt trailing edge profiled body are examined through experimental measurements of velocity and the spanwise distribution of fluctuating surface pressure on the model rear face near separation. Spatial and temporal variability of the vortex shedding Behaviour Result in low-frequency modulation of the pressure signals. The time-dependent amplitude is characterized using the wavelet transform, while subsequent correlation analysis and reduced-order modelling provide quantitative evidence of the dominant influence of large-scale instabilities. The cross-correlation of the wake velocity and the surface pressure are examined in the framework of the Extended Proper Orthogonal Decomposition, through which reduced-order models of the measured variables are related to construct an empirical estimator of velocity. Implications of the observed modal correlations and the statistical signature of large-scale spatial variations are discussed in relation to the estimation of multi-scale wake phenomena.